Root Architectural Development and Yield Sensitivity of Phosphorus Tolerant Common Bean under Low Soil Phosphorus and Drought

Abstract

Aims: The study assessed the effect of limited soil phosphorus and drought on yield sensitivity and root architectural development of low phosphorus tolerant common bean (Phaseolus vulgaris L.) materials Study Design: This was a randomised complete block design in which 2*3*5 factorial treatment combinations of drought, P levels and genotypes, respectively. Place and Duration of Study: The study was carried out in Central Uganda; Nakasongola representing a drought-stress and Mukono Zonal Agricultural Research and Development Institute (MUZARDI) representing non-drought-stress for two rainy seasons (March-June and August -December 2014). Methodology: In each study site, four low phosphorus tolerant genotypes (AFR703-1, AFR708, JESCA, and MCM2001 using K131 as a local check) were planted in plots treated with 0, 60 and 160 kg P ha-1 in the form of Triple Super Phosphate. Results: The P-treatments neither had significant influences on grain yield nor root response; and no significant interactions with drought and genotypes. Yield did not significantly vary by drought treatments, but by genotypes (P<0.001), with AFR708 registering the highest yield of 1122 kg ha-1. Drought-stress induced significant root development, namely adventitious roots, tap and lateral root lengths, and total root lengths, in some genotypes.  Genotype AFR703-1 and AFR708 had an edge over the local check; they produced multiple root systems.  Conclusion: Under drought stress, the AFR gene pool was superior in root development, namely number of adventitious and lateral roots, and taproot and lateral root length. In contrast, grain yield of these materials was suppressed by drought stress.